A Study of ZN-c5 and Abemaciclib in Participants With Breast Cancer

A Phase 1b Study of ZN-c5 in Combination With Abemaciclib in Patients With Estrogen-Receptor Positive, Human Epidermal Growth Factor Receptor-2 Negative Advanced Breast Cancer

Status

Completed

Phases

Phase 1

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT04514159

Enrollment

Registered

2020-08-14

Start date

2020-11-12

Completion date

2022-10-24

Last updated

2023-02-01

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Breast Cancer

Keywords

Dose escalation, Phase 1 combination, Selective estrogen receptor degrader, Hormone sensitive, Estrogen receptor, Hormone receptor

Brief summary

This is a Phase 1b, open-label, multicenter, dose-escalation study to evaluate the safety, tolerability, pharmacokinetics (PK), and preliminary efficacy of ZN-c5 administered orally in combination with abemaciclib (VERZENIO®) in participants with advanced estrogen-receptor positive, human epidermal growth factor receptor-2 negative (ER+/HER2-) breast cancer.

Interventions

DRUGZN-c5

ZN-c5 is the study drug.

DRUGAbemaciclib

Abemaciclib (VERZENIO®) is an approved drug.

Study design

Allocation

Intervention model

SINGLE_GROUP

Primary purpose

TREATMENT

Masking

NONE

Intervention model description

All participants will receive the same treatment but ZN-c5 will be given at different doses in this dose escalation study.

Eligibility

Sex/Gender

ALL

Age

18 Years to No maximum

Healthy volunteers

Inclusion criteria

* Age ≥ 18 years of age * Women can be peri- or postmenopausal, as defined by at least one of the following: * Age ≥ 60 years; * Age \< 60 years and cessation of regular menses for at least 12 consecutive months with no alternative pathological or physiological cause; and serum estradiol and follicle-stimulating hormone (FSH) level within the laboratory's reference range for postmenopausal females; * Documented bilateral oophorectomy; * Must receive a gonadotrophin-releasing hormone agonist beginning at least 4 weeks prior to the first dose of study medication * Histologically or cytologically confirmed diagnosis of advanced adenocarcinoma of the breast * Estrogen receptor positive disease * Human Epidermal Growth Factor Receptor 2 negative disease * Measurable disease per Response Evaluation Criteria in Solid Tumors v1.1

Exclusion criteria

* Prior therapy within the following windows: * Tamoxifen, aromatase inhibitor, fulvestrant, or other anti-cancer endocrine therapy \< 14 days; * Any investigational drug therapy \< 28 days or 5 half-lives (whichever is shorter) * Any prior systemic chemotherapy regardless of the stop date, but the subject must have recovered to eligibility levels from prior toxicity * Prior treatment with CDK4/6 inhibitors * Unexplained symptomatic endometrial disorders (including, but not limited to, endometrial hyperplasia, dysfunctional uterine bleeding, or cysts)

Design outcomes

Primary

Measure	Time frame	Description
Incidence and severity of adverse events from ZN-c5 in combination with abemaciclib	Through study completion, anticipated to be 21 months	Measured by the number of treatment-emergent adverse events and graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) v5.0

Secondary

Measure	Time frame	Description
Determine tumor responses to combination treatment	Through study completion, anticipated to be 21 months	Measured by radiographic responses as defined by revised Response Evaluation Criteria in Solid Tumor (RECIST) v1.1.

Countries

Poland, United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026